| Extension | F3D |
| Full Name | Fusion 360 |
| Type | CAD |
| Mime Type | application/octet-stream |
| Format | Binary |
The F3D format is a purpose-built file format created by Autodesk for use with their Fusion 360 Computer Aided Design (CAD) software. Fusion 360 is popular for use in various engineering and manufacturing sectors, with the format continuing to evolve with new features added with each new release.
Contained within an F3D file is the 3D object, along with its associate elements. These are defined in a manner that incorporates a complete history of the object, allowing adjustments to be made to earlier parts of the object while maintaining the final valid 3D model.
As F3D files can only be opened using Fusion 360, support for opening these files with other software is limited. Fusion 360 does offer export options for STEP, STL, and other popular formats, meaning F3D files can be indirectly converted to other formats and consumed by other CAD applications relatively easily.
The STL, or Standard Triangle Language, file format has been around since the '80s and is supported by most modern 3D modeling applications. In particular, the STL format has become something of a standard format within the area of 3D printing, despite the rise of more modern formats such as 3MF.
STL files come in two flavors: binary or text format. The text format is human-readable, making it easy to perform manual edits, but can lead to very large file sizes. As you can imagine, the binary format is much more compact and represents the majority of the STL files you are likely to encounter.
The format itself is very simple; the 3D model is represented by a sequential list of triangles, with each triangle defined with 3 points consisting of their X, Y, and Z positions, along with an additional vector that contains the face normal (the direction the face is pointing). There is an additional attribute block for each triangle; however, this is largely unused and thus unsupported.
